Radio transmitter



.Jan, 13, 1942. R. AUBERT ET AL RADIO TRANSMITTER Filed Sept; 2, 1939 4 Sheets-Sheet 1 INVENTORS ROGER AUBERT RA 0 WLLEM ATTORNEY.

Jan. 13,1942. A R ETAL 2,270,157

RADIO TRANSMITTER Filed Sept. 2, 1959 4 Sheets-Sheet 2 INVEN OR ROGER AUBERT T s RAYMOND V/LLE'M ATTORNEY.

Jan. 13 1942. I R. AUBERT ETAL). 2,270,157

RADIO TRANSMITTER Filed Sept. 2, 1959 4 $lieet-Sheet 3 JNVENTO ROGER AUBERT Rs BY RAY/W0 0 V/LLEM ATTORNEY.

Jan. 13, 1942. R. ALTI'BERT ETAI.

' RADIO TRANSMITTER Filed Sept. 2, 1939 4 Sheets-Sheet 4 m Y m W fi m m mL T 18 A MX M W km V. B

Patented Jan. 13, 1942 RADIO TRANSMITTER Roger Aubert and Raymond Villem, Paris, France,

assignors to Compagnie Generale de Telegraphic Sans Fil, a corporation of France Application September 2, 1939, Serial No. 299,152 In France September 14, 1938 8 Claims.

This invention relates to improvements in oscillation circuits of high frequency transmitters.

It is known that in the production of transmitters for very high frequency, the difliculties increase very rapidly with the power to be handled.

These difficulties are due in part to the larger dimensions of the various organs and also the corresponding increase in the parasitic capacities of the oscillatory circuit. The establishment of little circuits necessary to obtain short wavelengths, entails difficulties which are greater because the smaller physical dimensions of the circuits require a great dissipation of energy, and they often include switching systems. The provision of wave switches in these circuits is moreover a delicate matter especially in the case of very strong high-frequency currents.

The present invention has for its object to overcome these drawbacks.

A first part of the invention relates to certain modes of embodiment of the self-inductances of the oscillating circuit, and their connections with the vacuum tubes of the circuit also the wave switches are arranged to handle high powers without causing high losses in high frequency'by providing cooling means.

At this portion of the specification distinction is made between two cases; of the first part, one case is directed more especially to the tuning of the circuit to several predetermined wavelengths, the other one'to the tuning of the circuit which will be rendered variable in a continuous fashion by acting exclusively, or almost exclusively on the self-inductance.

A second part of the invention is concerned more especially with the disposition of neutrodyne condensers which are utilized in such circuits.

The invention will be better understood in reference to the accompanying figures which represent the various modes of construction of the invention. It should, however, not be limited precisely thereto.

. Fig. 1 represents the arrangement in perspective according to the invention of an oscillating circuit with several waves fixed in advance.

Fig. 2a is an elevation of an inductance arrangement;

Fig. 2b is a cross-section of Fig. 2a;

Fig. 3a is a plan view of another inductance arrangement;

' Fig. 3b is a front elevation of Fig. 3a; Fig. 4'is an enlarged section of Fig. 2b;

Fig, 5a is an elevation of a tube arrangement with spaced metallic members forming neutrodyne capacities;

Fig. 5b is a section through the arrangement of Fig. 5a.; and

Fig. 6 is a perspective view of a pair of tubes and spaced capacitive members of Figs. 5a and 5b.

Referring now in detail to Fig. 1 of the drawings, the coolin tanks of the tubes are shown in a symmetrical arrangement and indicated at l and 2. The self-inductances permitting the tuning of the transmitter to three wave lengths are shown at 3, 4 and 5.

The self-inductance 3 is to be permanently connected to the tank of the tube and is passed by the cooling water for the latter. The water inlets and water outlets are at the point of zero high frequency potential to avoid the losses in the cooling water. This self inductance is so calculated that when utilized alone it corresponds to the longest wave to which the transmitter should be tuned.

The self-inductance 4 is such that when connecting its extremities to the tank of the tube, there is obtained the next lower wave to which the transmitter should be tunable.

The self-inductance 5 is dimensioned to furnish in turn a third transmission wave when it is connected, the self-inductance 4 may or may not remain in service.

In accordance with the invention, the self-inductances 4 and 5 formed each by two tubes, are cooled by circulating water and connected respectively in the center thereof to avoid high frequency losses.

These water circulations reach the extremities of the self-inductances so as to assure at these points an effective cooling. The contacts taps l5 to 20, inclusive, are arranged to have a switch (not shown) which switch has spring clips 2| and 22 attached thereto. The spring clips 2i and 22 are slidably arranged to be connected at one end to the extremities of the self inductances and at the other end to the tanks of the tubes l and 2. They are thus arranged to be in close touch with well cooled parts. It is possible, instead of establishing the connection at the tanks of the tubes proper, to make the connection at the contact taps electrically connected to these tanks and cooled respectively by the water circulating through the corresponding tube.

On account of the short length, the contact taps withstand very high currents. They could moreover be provided with cooling fins in order to increase their thermic dissipation.

It would also be possible to cool these contact taps with circulating water, without entailing high frequency losses, by connecting them with a flexible tube to the end of the self-inductance corresponding to each respective contact tap.

It is rather important to arrange the selfinductan'ce corresponding with the shortest wavelength towards the top of the tank of the tube. In this way, the self-inductance due to the said tank will actually be reduced.

In order to increase the number of tunablewaves without increasing the number of selfinductances, or to adjust the value of the latter, short circuit connections could finally be arranged which operate in symmetrical points of the center of each self-inductance.

According to the invention, this commutation.

is carried out preferably with the aid of contacts likewise cooled by circulating water and receiv-.

ing this water at their center part which has zero high frequency potential.

Such a contact arrangement isv represented.

schematically in an elevational view and. in cross section in the Figs. 2a and 22). It comprises several elements connected in parallel and so disposed as to distribute among themselves the current in a substantially equal manner.

This contact arrangement includes essentially a solid piece ll forming a favorable conductor in direct contact with the cooled tubes of the self inductances, a certain number of flexible con- I tacts 12 extended from H, and an equal number of flexible springs 13 insulated from the contacts l2 by means of insulating blocks l4 so as not to be passed by current and to retain their mechanical qualities. The contact is established by means of the hollow piece l5 cooled by water.

The coupling of the utilization circuit with the multiple self-inductance described above is established either in parallel to each of the elementary self-inductances, or to the selfinductance 3.

The Figures 3a and 3b represent as a variation an arrangement likewise conforming to the invention and in relation to the case of a circuit whose tuning is variable in a continuous fashion by the modification of the self-inductance.

This self-inductance then consists substantially of two circular arcs 3l32 formed by two tubes having a quadratic cross section for instance and also permitting to lead the cooling water of the tube to a point having, as regards high frequency, zero potential. These two circular arcs are joined by means of a sliding metallic piece 33 carried by an insulating arm 34 which pivots about an axis passing through the center of the circle.

This metallic piece 33 can be cooled by circulating water as shown in Fig. 4.

The shaft of the insulating arm 34 also carries two other arms I, 8, with two jaws 35, 36 which glide on the self-inductances and which are insulated from the aforesaid metallic piece such as to permit the coupling of the oscillating circuit with the utilization circuit. The position of these jaws with respect to that of the piece. 33. can be controlled at will.

The invention provides in the second part a special arrangement of the neutrodyne condensers and of the condensers of the oscillating circuit.

It has been already mentioned that one of the principal factors determining the shortest wavelength to which a circuit can be tuned is the natural capacity of the elements forming it. The influence of this natural capacity is as such proportional to the square of the high-frequency potential to which the considered element is subjected.

In the high-frequency amplification circuits, the anode and its cooling container are brought to high-frequency potential. Their natural capacity relative to the surrounding masses plays a maximum role in obstructing the realization of very short wave lengths.

According to a mode of construction of the invention, the neutrodyne capacities are constituted by two armatures, the one being formed by the container of the tube proper, and the other one by a metallic surface which surrounds the container almost completely so as to catch almost the entire lines of force issued by the said container.

In this manner, the injurious natural capacity of the container of the tube will be replaced by a useful neutrodyne capacity, while the natural capacity of the exterior armature will be without influence upon the wave-length of the oscillating circuit in view of the fact that its high-frequency potential as viewed from the output circuit is found to be null if the compensation is exactly adjusted to.

In practice, the exterior armature of the neutrodyne condensers comprises a variable part for the control of same.

For facilitating the exploitation and the control it will be of importance to retain a low variable capacity constituting the physical element of the total capacity of the circuit.

This capacity should not present an appreciable residual capacity, and it should not act upon the control of the neutrodyne capacity.

To this end, in accordance with the invention, this capacity will be arranged to great advantage at the lower part of the tank of the tube. It will be separated, moreover, from the exterior armature of the neutrodyne capacity by a metallicscreen placed at the anode potential. In this manner, the movement of the variable tuning capacity will be Without influence upon the value of the neutrodyne capacity.

These latter arrangements are represented, by way of example, in Figs. 5a, 5b and 6, in which item 5| designates the tanks of the tubes, while 52 designates the exterior armatures of the neutrodyne capacities, 53 the movable armatures of the tuning capacities, 54 the electrostatic screens and 55 the insulating supports which carry the tubes.

What we claim is:

1. In a short wave oscillation generator comprising a structure in which a liquid may be circulated at least one thermionic tube having a liquid-cooled jacket, said oscillation generator structure connected with said tube, means for circulating a liquid in said tube liquid cooled jacket and said oscillation generator structure, said oscillation generator having at least a hollow inductance with hollow movable contact members and a variable tuning condenser, said tube liquid cooled jacket forming one of the electrodes of said condenser, the other one of said electrodes of the condenser being arranged to be variable at an end of said liquid cooled jacket, and means to cause a chilling liquid to flow through the oscillation generator structure with an outgoing and return circuit in the movable contact members and said hollow inductance.

2. In a short wave oscillation generator comprising a structure in which a liquid may be circulated at least one thermionic tube having a liquid-cooled jacket, said oscillation generator structure connected with said tube, means for circulating a liquid in said tube liquid cooled jacket and said oscillation generator structure, said oscillation generator having at least a hollow inductance with hollow movable contact members and a variable tuning condenser, said tube liquid cooled jacket forming one of the electrodes of said condenser, the other one of said electrodes of the condenser being arranged to be variable at an end of said liquid cooled jacket, and means to cause a chilling liquid to flow through the oscillation generator structure with an outgoing and return circuit in the movable contact members and said hollow inductance, said last mentioned means comprising a hollow movable contact piece located on said hollow inductance and serving as an envelope for a double channel on which elastic fixed contacts come to bear.

3. In a short wave oscillation generator comprising a structure in which a liquid may be circulated at least one thermionic tube having a liquid-cooled jacket, an oscillation generator structure connected with said tube, means for circulating a liquid in said tube liquid cooled jacket and said oscillation generator structure, said oscillation generator structure having at least a hollow inductance with hollow movable contact members and a variable tuning condenser, said tube liquid cooled jacket forming one of the electrodes of said condenser, the other one of said electrodes of the condenser being arranged to be variable at an end of said liquid cooled jacket, and means to cause a chilling liquid to flow through the oscillation generator structure with an outgoing and retum circuit in the movable contact members and said hollow inductance, said last mentioned means comprising a double circular helix with two hollow tubes united by a sliding metallic piece and cooled by circulating liquid.

4. A short wave oscillation generator comprising an oscillation circuit, a pair of thermionic tubes each having a liquid cooling jacket, said oscillation circuit including a pair of inductances and a pair of variable condensers, said tube cooling jacket of each thermionic tube forming one electrode of each one of said condensers, the other electrode of each one of said condensers being variably arranged at an end of said thermionic tube cooling jackets.

5. Short wave oscillation apparatus comprising an oscillation circuit, a thermionic tube having a liquid cooling jacket, said oscillation circuit including an inductance and a variable condenser, said tube cooling jacket forming one electrode of said condenser, the other electrode of said condenser being variably arranged at an end of said thermionic tube cooling jacket.

6. Short wave oscillation apparatus comprising an oscillation circuit, a pair of thermionic tubes each having a liquid cooling jacket, said oscillation circuit including a pair of inductances and a pair of variable condensers, said tube cooling jacket of each thermionic tube forming one electrode of each one of said condensers, the other electrode of each one of said condensers being variably arranged at an end of said thermionic tube cooling jackets and insulated therefrom.

'7. Short wave oscillation apparatus comprising an oscillation circuit, a thermionic tube having a liquid cooling jacket, said oscillation circuit including an inductance and a variable condenser, said tube cooling jacket forming one electrode of said condenser, the other electrode of said condenser being variably arranged at an end of said thermionic tube cooling jacket, and an electrostatic screen insulatingly supported above said other electrode.

8. Short wave oscillation apparatus comprising an oscillation circuit, a pair of thermionic tubes each having a liquid cooling jacket, said oscillation circuit including a pair of inductances and a pair of variable condensers, said tube cooling jacket of each thermionic tube forming one electrode of each one of said condensers, the other electrode of each one of said condensers being variably arranged at an end of said thermionic insulatingly supported above said other electrode.

ROGER AUBERT. RAYMOND VILLEM. 

